填空。

①You mustn't walk around during landing. ____   A. On a bus

②You mustn't talk to the driver.____         B. On a train

③You must wear a helmet .____          C. On a bike

④You must wear a seatbelt.____           D. On a car

⑤You mustn't put your head out of the window.____   E. On a plane

⑥You must wear a lifejacket.____       F. On a boat